NFS: fix unsigned comparison in nfs4_create_sec_client

fs/nfs/nfs4namespace.c: In function ‘nfs4_create_sec_client’:
fs/nfs/nfs4namespace.c:171:2: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]

Introduced by commit 72de53e
"NFS: Do secinfo as part of lookup"

Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4namespace.c

@@ -168,7 +168,7 @@ struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *ino
 	rpc_authflavor_t flavor;
 
 	flavor = nfs4_negotiate_security(inode, name);
-	if (flavor < 0)
+	if ((int)flavor < 0)
 		return ERR_PTR(flavor);
 
 	clone = rpc_clone_client(clnt);